DVD: Knight and Day, For retail & rental (20th Century Fox)

A limp romantic comedy that copies The Bourne Identity might sound like an ideal vehicle for, say, Gerard Butler and Kate Hudson.

But what megastars of Tom Cruise and Cameron Diaz's wattage are doing in it is a mystery. He's a rogue secret agent, she's an innocent who gets caught up in his escapades, but beyond that neither of them has much of a personality, and the villains have even less. A watchable but unmemorable B-movie.